How can distance of galaxies can be identified from the earth?

Answer 1

If we know the luminosity of stars in other galaxies, we could work out their distance by measuring their apparent brightness. Its a simple process.

Answer 2

There are several methods used to assess the distance to a galaxy. For moderately distant galaxies, supernova with a known and dependable time to brightness curve, allow the derivation of the distance to a galaxy (of course, you have to wait for a star to go supernova in that galaxy) as a function of how bright at its maximum it appears to us here.
For very distant galaxies, the red shift value (due to the expansion of the universe) can be used, but local variations in the speed of specific galaxies require checking neighbors galaxies as well, since the rate would then apply to the cluster, and not to the individual galaxies that make the cluster.

Answer 3

The primary source of distance information is the use of stars of known absolute magnitude (brightness). These are called "standard candles". If we know how bright something really is, we can tell how far away it is by measuring its apparent brightness, knowing that the intensity of light decreases proportional to the square of the distance.

The first brightness standards were Cepheid variables, stars that vary in brightness with a period related to their absolute magnitude. Type Ia supernovae are another important standard candle because they can be seen over very great distances.

Early on, Edwin Hubble noticed that there was a correlation between a galaxy's distance and the speed at which it was moving away from us as indicated by its red shift. In recent years this relationship has been calibrated using standard candles, so the distance to very distant galaxies is usually based on their red shift.

Answer 4

Hold on,I'll be back in 20 minutes with an answer.I have got to do something else now.

There are several methods used to assess the distance to a galaxy. For moderately distant galaxies, supernova with a known and dependable time to brightness curve, allow the derivation of the distance to a galaxy (of course, you have to wait for a star to go supernova in that galaxy) as a function of how bright at its maximum it appears to us here.
For very distant galaxies, the red shift value (due to the expansion of the universe) can be used, but local variations in the speed of specific galaxies require checking neighbors galaxies as well, since the rate would then apply to the cluster, and not to the individual galaxies that make the cluster.

I apologize for copying his answer.I was in a real hurry.If you don't report me and SELECT THIS ANSWER AS THE BEST,I'll select your answers as the best and I'll give you stars.Come on,be a friend.

AND GIVE ME SOME THUMBS UPS,NOT THUMBS DOWNS!!!!

RRRRRRRR,YOU IDIOTS,I SAID THUMBS UPS!!!!!!!!

THHHHHHHHHHHHAAAAAAAAAAAAATTTTTTTTTTT """SSSSSSSSS ITTTTTT.You are dead!!!!!!!!!ALL I ASK FOR IS THAT PEOPLE GIVE ME THUMBS UPS ON MY ANSWERS AND TO GET A BEST ANSWER BUT NOO,SOMEONE FORGOT 'TO FLUSH THE TOILET' AND IT STINKS.THAT'S what I ASKEd for.IS THAT TOO MUCH TO ASK!!!!!!!!!!!!!!!!!!!